Method of purifying brines



J. B. PIERCE. JR

METHOD OF PURIFYING BRINES Filed Dec. l5, 1938 Feb. 20,4940.

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ATTORNEYS `Patented Feb. 20, 1940 UNITED STAT .lames B. Pierce, l

Es, PATENT OFFICE t METHOD or roam-YI'NG nimmst Y.

Jr., Charleston, Va., as-

signer to 'Standard Ultramarine Company,

Huntington,v- W. Virginia' .s a corporation of `West f Application December 13, iosaseriailm; 245,412 s claims. (el: 232:45)

This invention relates to the 'purifying of brine andother liquors containing as impurities therein--watersoluble sulphates and cipal objects the provision of aV simple, econom- 'lf' ical, expeditious and effective method for accomplishing such removal.

.Natural salt brines usually contain water-"b more especially those of calsoluble sulphates,

' Heretofore it has cium, magnesium and sodium.

'10A been customary, particularly Where such` brines were intended for use in the manufacture of. soda ash,..electrolytic .caustic and chlorine, to employ e purpose of effecting the removal of the sulphate radical but such treat-` v lbarium chloride for the ment,however, is Wholly ineffectivev for the purpose of removing the lime and magnesia radicals.

Furthermore, barium chloride, even-ifit were entirely suitable for the purpose, is relatively costly being some more expensive than barium ycarbonate, the agent employed by me in the purification method hereinafter described.-

Commercial: air-floated Wtherite barium carbonate, has an averag'eparticle size of. about 2.55 microns and a 4specific surface 'of 0.547 sq. meter per gram and even precipitated barium carbonate prepared in accordance l'With the method described in ,0.44`flmicron and a specific surface of some`3z145 scpmeters per gram. Such products: of other ticle size and compared with the super-reactive bariumcarbonate employed by me -in the method herein-'- 3 'after' described and arevnot adapted'for' the suctheyware not'sufdciently'reactive to eifectivelyre- 'move lime and magnesium radicals fronij the' 5 million of the tieni y `Intheevent such small amount of sulphate radical cannot be tolerated'by the manufacturer, thejsame canbe eliminated by the addition of 'a chemical equivalent amount ofbarium chloride following the herein' described treatmentvvith super reactive barium carbonate. c y s The theoretical explanation of the effectiveness of? the super reactive' barium carbonate employed 6o bym'effo'r effecting the removal of the sulphate,

has for its prin-k (l) BaOOa-l-QaS'O;

l bilities ofthe i. e'. natural Y my prior Patent No.` 1,774,523fhas7an average particle size foffsome barium carrbonatesv are .of relatively large parrelatively small specificfsurface as salt solution'rin contact"Withy air as of; the 2.68' grams forwaterQ cessful purification of salt'k brine solutions sinceV y a complete removalfof lthe sullime andmagnesia radicals from salt brines can be best-appreciatedby reference to' the following reactions: 1

BaSorx-oaoo. e t .002s .300 u The rfigures under the chemical symbols are solubilities inwater of the compound represented by the symbol iny grams per liter at the' temperature indicated, as given in Seidells solubility tables. 'l v vr"Ihese solubilitiesVasv given, dov not of course take into consideration-1 the effect Aon the solunearly saturated salt solution instead of Water; however, the controlling factor that causes Reactionsu l, A2` and the right. is the fact that barium sultim'es more insoluble in water' than barium"v carbonate, andwe can with assurance reasonthatL this differential in solubilitiesA will 3 to proceed to completion various 'compounds caused by the not befmaterially altered by the saturated salt s solution. l I

Seidell gives1 the solubility of MgCO.I in a 25% .923 gram This'will `of lcourse cause Reaction 2 to proceed 'to' practical completion to the right -andexplains WhyV We nd* only ja trace of magnesium injtheA purified saltgb'rine Seidell` gives the solubilityo-f :CaCOa in av 25% salt solution in contact with air as .085 gram per liter, insteady of the .-300gramfor Water.

This Will of course cause Reaction l to proceed to practical completion to the right..

`Both NazCOa V- and Na2SO4 are so soluble in either wateror a 25% salt solution that Reaction 3 depends for its driving lforce to the right altogether on pared with barium carbonate, but as ABaCOs` is relativelyinsoluble a time element enters here to complete the removal of the S03 equivalent of the NazSOi.

. 'I he accompanying drawing is a graph ofthe reactivity at the" temperatures' specified'` of the aforesaid super-reactive barium-carbonate employed bysme in the purification of brines with a vbrine containing calcium, magnesium and sodium sulphate in an amount equivalent vto 1.500 gms. -S's perliter.

' As contrasted tofthe` reactivity of the aforesaid f super reactive barium carbonate towards calcium,

the insolubility of llBaSOi` as comf45 micron and a specific surface of 3.145 sq. meters per gram; and also commercial air-floated witherite i. e. natural barium carbonate (designated #3) which has an average particle size of 2.55 microns and a speci-o surface of 0.547 sq. meter per gram,.representing 0L027 concentrations of the calcium, magnesium and sodium sulphate solutions are 0.0021018 gram per ml., 0.0017874 gram per ml. and 0.0020168 gram per ml. respectively.`

The aforesaid super reactive barium carbonate having an average particle size of considerably less than 4 microns desirably about 0.234 micron and a specific surface considerably greater than 4 sq. meters per gram and desirably about 6 sq. meters per gram or corresponding to about 36.2 trillion particles .per gram is preferably prepared as followsn' 4500 ml. (milliliters) of f liquor heated to between C. and 90 C. and of about 9.5% BaS content is introduced into a cylindrical container .or absorber of a turbo mixer,

a barium sulphide illustrated in Patent No. 2,081,112, said container preferably being of a capacity of10,000 ml. Approximately 20% by volume of carbon dioxide gas is then introduced into theabsorber while the liquor is being rapidly agitated therein by means wheel thereof so that the gas disproximity to such wheel and preferably discharges immediately below a baffling dome mounted immediately above such Barium carbonate Percent reacted between- #l #2 #3 m Calcium sulfate: g Percent Percen Percent In 15 minutes; 15. 0 4. 6 6. 05 30 minutes- 37. 0 l0. 6 11. 2 60 minutes.. 90. 5 30. 1 21. 8 Magnesium. sulfate:

minutes.. 29. 9 24. 5 18. 1 34. 9 28. 9 20. 5 40. 4 34. 4 24. 3

super barium carbonate, the same being added thereto in dry form while vigorously agitating the mixture either mechanically or pneumatically or by pressure circulation thereof. The said super jreactive barium carbonate will precipitate the -'sulphate radical of the water-soluble sulphates present in the mixtures as barium sulphate and will precipitate the lime and magnesia radicals as calcium carbonate and magnesium carbonate respectively. 1

Preferably the'brine is heated to a temperature of from 19 C. to` 50, C. while being vigorously during the rst hour, whereupon' the agitation is discontinued and the temperature raised Vto approximately 80 C. at which temperature the reactionis Vallowed to continue for anradditional 24 hours. Following the completion of the `reaction the precipitated products are allowed to settle and the clear liquor is then decanted `ol' therefrom or, vif desired, in lieu of such decantation, the purified brine can be separated `by ltr'ation from the precipitated Abarium sulphate together with carb`o'- nates of calcium, and magnesium.

Various `modifications both as regards the physical dimensions of the particles of the super reactive'barium carbonateemployed in the above describelgY method of treating salt brines, as well as in the temperature maintained during the treatment and the time of agitation, as well as the time oftotal treatment, within the scope of the `appended claims, may be madewithout Ele-l parting from the spirit of my invention.

Having thus described my invention, what I claim and desire to obtain by Unitedl `States Letters Patent is:

, 1. The method of purifyingV salt brines and other liquors' containing a plurality of watersoluble sulphates, .including `calcium or magnesium sulphate as impurities, which comprises agitating the same with an amount of a precipitatedA super-reactive barium` carbonate vwhich is at least about theV chemical equivalent by weight of a water-soluble sulphate present inf the liquor agitating the same with an amount of a precipitated super-reactive barium carbonate which is and then separating the resultant precipitate vfrom the liquor of the mixture.

3. 'Ihe method of purifying salt brines and water-soluble which barium carbonate has been dried subsequent to such prev and the subsequent cipitation and has a particle size of less .than 0.35 micron and is of a specific surface of at least about 4.5 sq. meters per gram, then discontinuing such agitation and while the liquor is substantially quiescent, maintaining the liquor at a temperature in excess of 75 C. for a' prolonged period of time and several times the original period of agitation to eiect completionr of thereaction of such barium carbonate ori phates, and then separating the resultant precipitate fromv the liquor of the mixture.v f

4. The method of purifying salt brines and other liquors containing a plurality Y'off watersoluble sulphates, including calcium or magnesium sulphate as impurities, which comprises agitating the same for a relatively short period, notl exceeding a few hours and while at a'temperature between about 60 C. and 15 C.,

barium carbonate which is at chemical equivalent by Weight of a water-soluble cipitation and has the period of with an amount of a precipitated super-reactive least about the sulphate present in the liquor and which barium carbonate has been dried subsequent to such prea particle size of less than 3 a specific surface of at least per gram, then While the microns and is of about sq. meters such agitation and of agitationto effect completion of the reaction of 4such barium carbonate on the soluble sul- 5. In the method as claimed in claim 4, wherein the period of agitation is less than 2 hours and rtreatment while the liquor is quiescent exceeds 20 hours. f

A6. In the method as claimed in claim 4, wherein the period of agitation approximates 1 hour not exceeding the? soluble' sul- C.,

the same is v discontinuing.

liquor is substanl. `tially quiescent, maintaining the liquor at a temperature in excess of '75 C. for a prolonged period of `time and several times the original period period of treatment while the liquor is quiescent is at least abouti24 hours.

7. The method of purifying salt brines' and other liquors containing a plurality of watersoluble sulphates, including calcium or magne- [siuml sulphate as impurities, which comprises agitating the same for a relatively short period, -a few hours and while the same is at a temperature between about 60 C. and 15 with an amount of a precipitated superreactive barium carbonate which is at least about the chemical equivalent by weight of a watersoluble sulphate present in the liquor and which barium carbonate has been dried subsequent to such precipitation and has a particle size of less than 0.25 micron and is of a specific surface of at least about 5 sq. meters per gram, then discontinuing such agitation and while the liquor is substantially quiescent, maintaining the liquor at a temperature in excess of '75 C.. for a prolonged period of time and several times the original period of agitation to effect 4completion of the'reaction of such barium carbonate on the solublesulphates; and then separating'rv the` resultant precipitate from the liquor of thev mixture.

8. The method of purifying salt brines and other liquors containingv a plurality of water- `soluble sulphates, including calcium or magnesium sulphate as impurities, which comprises agitating the same with an amount of a precipitated super-reactive barium carbonate which is at least about the chemical equivalent by weight of a kwater-soluble sulphate present in the liquor and which barium carbonate has a particlesize of less than 0.25 micron and is of a specific sur-1 face of at least about`5 sq..meters vper gram;V

and then separating the resultant precipitate from the liquor of the mixture.

Jar/ins B. PIERCE, JR 

